send batch message with tag, commitlog save tag error

[Bin2020]

版本4.9.2，发送批量消息，tag设置TagA。commitlog保存的消息TAGS为TagACLUSTER，漏了分隔符。消费者订阅TagA收不到该消息。如果订阅全部类型tag，打印该消息的TAGS为TagACLUSTER�DefaultCluster

BenchmarkTest mKEYS�OrderID002�UNIQ_KEY�7F000001023818B4AAC23171A8B90001�WAIT�true�TAGS�TagACLUSTER�DefaultCluster�WAIT�true 

[HScarb]

#2961
this PR modifies MessageDecoder#messageProperties2String() may cause this problem, as it deleted last character of the properties string
as we see, @areyouok has working on it to fix this bug

[areyouok]

I have fix it, test finished.

You can pick this commit and build it yourself before 4.9.3 release.